1. Field of the Invention
The present invention relates to the security of a system capable of externally activating a device loaded with a radio, and more specifically to the technology of switching security at system shutdown.
2. Description of the Prior Art
Recently, a wireless system has been structured a number of techniques have been proposed to improve the convenience to a user. For example, there is the technique of activating a user PC by way of a LAN depending on the necessity from a remote area such as a WOL (wake up LAN), etc.
However, a technique such as a WOL, etc. is actually convenient, but it is very important to set a security technique to suppress the leak of the data during wireless communications. As a system using the WOL, a POS system (point of sales system) in a store, etc. is described below. Using the Internet, etc. from a remote area (user home), a PC of a head office is accessed, a POS terminal (register for POS of a client) is activated through an AP (access point of a radio base station), price information, etc. is acquired from the head office, and the database of the POS terminal is updated. These operations are normally performed before opening a store each day, and updating a database takes a long time. Therefore, it is necessary to power up a POS terminal in advance through a WOL. When a database is updated, important data such as price information, etc. can be disclosed. Therefore, the encryption is required.
The patent documents 1 through 3 offer the propositions to improve the security against the leakage of data of a system using a wireless LAN such as a communication system for improving the security using a dynamic key and authentication data, a switch system as to whether or not encryption is to be performed, etc.
However, in the common wireless communication, when encryption is performed to ensure security, an encryption key is fixed if a WOL is used. For example, a WEP (wired equivalent privacy) is used. However, the system using a fixed key such as the WEP, etc. is less reliable than a system using a dynamic key. Therefore, it is considered to use a TKIP (temporal key integrity protocol) and an AES (advanced encryption standard) using a dynamic key. However, since an encryption key is dynamically changed in a high-level encryption system, a WOL cannot be easily realized. For example, since the same encryption key is to be used at the activation and termination, it is necessary to change the hardware and develop a dedicated driver.
In the patent documents 1 through 3, the communication system after the activation of a POS terminal is described, but they do not describe the system capable of entering an operation status without reducing the security level after the activation using a WOL.    [Patent Document 1] Japanese Published Patent Application No. 2004-72682    [Patent Document 2] Japanese Published Patent Application No. 2003-87289    [Patent Document 3] Japanese Published Patent Application No. 2005-73133